The present application relates for special techniques for cooling a special kind of bulb.
Special metal halide bulbs have special cooling requirements. The bulbs, such as Philips metal halide projection lamps, often have a central portion which emits light, and two xe2x80x9cpinchxe2x80x9d portions around the central portion.
A diagram of an exemplary one of these bulbs is shown in FIG. 1. The bulb has a central light emitting portion 100, and the two surrounding xe2x80x9cpinchxe2x80x9d portions 102, 104.
In some bulbs, it is desirable to keep the pinch portions 102, 104 cooler than the center portion. This is easy to do in a laboratory condition, but more difficult to do in practice.
While it may be possible easy to cool only an edge and not the center in a laboratory, the inventor recognized that doing this in practicality can be more difficult. For example, in a laboratory, the bulbs are often cooled using pipes of air. Those pipes could get in the way of the light output from the bulb, and/or the bulb""s reflector. Therefore, it has been difficult to cool these kinds of bulbs.
The present application teaches a way of cooling a bulb of this type, by cooling only a pinch portion, and not the center portion. This is done by using a special combination of structure that cools at least one of the edges, but does not cool the center.